E-Storesome basic pit falls
13 Jun 2007 00:42:08 IST
some basic pit falls
some basic points in oxygen family
1)the acidic nature of the hydrides is quite reversed of wat is expected, bond is most polar in H2O , so it is least acidic
order is H2O < H2S < H2Se < H2Te
2)Only S , Se , Te in grp 16 shows catenation property (all 8 membered rings), Oxygen exist is diatomic , Po is monoatomic
3)H2O has the highest M Pt. and B Pt., this is due to extensive H-Bonding (though is contradictory by vander waal's forces)
4)FRrom 273 to 277K densityof water increases i.e it contracts , bt after 277K , it starts expanding with increase n temp so H20 has max density at 277K or 4 deg C
5) Rhombic sulphur melts at 387.5 K to a thin pale yellow liquid , bt at 453K , it suddenly becomes so viscous that it cannot be poured out frm the vessel
6)Electron affinities of 16 grp elements follows the order
O < S >Se >Te
this is due to small size of oxygen , as a result of small size , interatomic repulsions in 2p subshell of Oare more than in 3p subshell of S atom and S has large atomic size than O
some more pts
a) All elements of 16th grp exhibit -ive oxdn state except Polonium
b)the 1st 4 mmbers are named as calcogens means ore forming bcoz most of metal ores are oxides or sulphides
c)Po is naturally occuring radioactive element
d)Oxygen shows +ive oxdn state only in its compds with F2 coz F is more electro-ive than O
e)conc. HNO3 + concH2SO4 is called nitrating mixture or mixed acid
f)H2S is poisonous and antidote fr it is dilute chlorine
g)m pts and b pts of hydrides
H20 > H2S > H2Se > H2Te
Volatile nature
H20 < H2S < H2Se < H2Te
reducing character
H20 < H2S <H2Se < H2Te
bond angle dipole moment , thermal stability
H20 > H2S > H2Se > H2Te
not taken frm any site , i have posted wat i prepared frm my notes , u can find it in books , bt wich book that i can't say , so i collected them here fr u
hope u like it :)
Comments (8)
shine
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Joined: 2 Mar 2007 17:23:44 IST
Posts: 273
13 Jun 2007 14:08:23 IST
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